The other day I was sitting outside my house with my friend. He and I were just sitting on the ground. There were a number of small black ants around us going about their business but not really in our way. After some time they began to fixate around the area I was sitting. They climbed on my feet and gave little nips and so on. After a while it got a little ridiculous so I moved to the other side of my friend where there were no ants at all. It was completely clear and not in (what I thought to be) their trail. It wouldn't have been more than five minutes later and then they were back again. They were all around me and the spot I had been in previously was completely clear. I just couldn't figure out what it was about me??? I should point out that my friend was left alone the entire time. It occurred to me later however that it had been "that time of month" for me and was wondering if they were reacting to the change of hormone levels?

Thanks for any help you can give me
CJ

Dear CJ,

I have never heard of ants being attracted to human hormones before but without doing an experiment, it would be difficult to say for sure what was happening. Ants would be more likely to respond to food smells. Were you carrying any food or had you been cooking recently? A sweet smelling perfume could also be attractive to ants. However, smells and insect responses to them are often unpredictable. For example, certain termites recognize pen ink chemicals as trail pheromones and can be tricked into following ink lines.

Thanks for your question,
Ben Rubin & the AntAsk Team

Dear Vidarshana,

This really is a great photo! Thanks for sending it to us! The darker ant in the center belongs to the genus Diacamma and the lighter ants surrounding and attacking it are members of the genus Oecophylla. The aggression between the ants may be the result of territoriality, predation, or a variety of other reasons.

Ben Rubin & the AntAsk Team

On Thu, Jan 3, 2013 at 4:33 PM, Allan wrote:

Greetings,

I have twin 4 year old boys who love ants. I brought them back a small ant farm from the USA, supplied with harvester ants from a nature store online. It is entirely self contained, with even edible gel for tunneling that prevents them from needing to be supplied with food.

I am following precautions regarding allowing them to get loose since I don't want to disrupt the local ecosystem. I am curious, are Harvester Ants native to Saudi Arabia?
Apparently they do well in arid regions, and there is plenty of that here.

Thanks & regards,

Allan in Saudi Arabia

Dear Allan:

Thanks for contacting our blog.

The harvester ants that come with ant farms in the USA belong to the American ant genus Pogonomyrmex, which only occurs in the Americas. Here is a nice map showing their distribution:
http://www.antmacroecology.org/ant_genera/Pogonomyrmex.html

Since your ants do not have a reproductive queen associated with them, there is no danger they would disrupt the local ecosytem, even if they did escape. But of course, you will wish to keep them contained for the enjoyment of your sons.

Now to your question about harvester ants in Saudi Arabia: Note that Ant Web has a site on the ants of Saudi Arabia:
http://www.antweb.org/saudi.jsp
There are in fact quite a few native harvester ant species in Saudi Arabia, in the genus Messor . These could be suited to rearing in an ant farm, once the ants you already have die off, as they will in a few weeks or months. Here's the page on Messor from the Saudi ants site linked above: http://www.antweb.org/description.do?rank=genus&name=messor&project=saudiants
They are about 1/4 inch long, and some of the species forage in the morning and evening, along conspicuous trails, in unirrigated areas.

It would be recommended, when you put new ants in the farm, that you substitute the gel medium with an inorganic digging medium such as slightly moistened sand or granular pumice. The ants can be fed grass seed, edible grains or hulled, unsalted sunflower seeds. Take care not to overfeed, as the uneaten food will spoil.

Happy ant farming, Stefanie Kautz and James C. Trager of the Ask Ant Team

From: Nancy
Subject: Thatch ants Washington State

We have a red-headed thatch ant colony more than six feet across near
large fir, cedar and big leaf maples. I am told variously that these
ants are beneficials, do not damage homes, are only moderately keeping
of aphids on ornamentals, and while they can bite if provoked, are
not dangerous. All this being said, my question is: Do they in any
way damage the trees, particularly the conifers, adjacent to their
nest? I would prefer to take the live-and-let-live approach and leave
them to enjoy their metropolis. We enjoy watching them and will leave
them alone if they aren't damaging the structure of the very large
trees near their mound.

Thank you in advance for your help.
Nancy

*************
Dear Nancy:

Thank you for your message to the ant blog. It sounds indeed like the ants you describe are the famous thatching ant, Formica obscuripes. The species abounds in some parts of the western conifer forests, and curiously, also extends south to the sagebrush plains of New Mexico and east to the prairies and old fields of Wisconsin and Michigan! Though it does befriend aphids, this may be considered the plant-to-ant equivalent of the cost of feeding a standing army. F. obscuripes is considered a beneficial insect over all, because of its prodigious predation of plant-eating insects, including such pests as spruce budworm. We applaud your live-and-let-live attitude, and are very pleased you chose to ask before acting.

Best regards,

James C. Trager of the Ask Ant Team

Hi there,

I live in Vancouver, Canada, and am wanting to establish an army ant farm. Can you suggest how best to go about this?

Thanks,
Paul
-----------

Dear Paul,

Starting an army ant farm in Vancouver, Canada could be very difficult for a number of reasons. First off, by nature, army ants are inherently nomadic predators, and thus keeping them in a confined space such as an indoor "farm" might be next to impossible if you want them to last very long. Secondly, most of the 5 genera of New World army ants (Cheliomyrmex, Neivamyrmex, Nomamyrmex, Labidus, and Eciton) are primarily Neotropical. While some species of Neivamyrmex have been seen as far north as Iowa (see this helpful ant distribution website), Vancouver is still hundreds of miles farther north, and with the cold humidity, it is doubtful any species of army ant could survive. Those that could for a short period would probably be subterranean, and you would need quite an arena to visualize and house a colony of thousands to millions of nomadic predators.

However, in 2005, Dr. Brian Fisher--myrmecologist extraordinaire--was able to import a colony of Eciton burchellii army ants to the California Academy of Sciences for the exhibit "Ants: Hidden Worlds Revealed". The advantage of importing Eciton burchellii in comparison to the many other army ant species is that they're generalists--they'll eat just about anything. The downside is that the millions of workers need a lot of space and have quite an appetite. Dr. Fisher informed me that Cal Academy was feeding the colony over 25,000 crickets a day, which they let loose in a giant chamber housing the colony in the museum.

Thus, unless you have the resources to build an arena and find the appropriate diet (smaller colonies will have more restricted diets--such as ant, wasp, or bee larvae), it might be a difficult task.

Best,

Max Winston and the AntAsk Team

Dear AntAsk,

I was wondering how thermoregulation works in ants?

Thanks in advance!
Farzaneh

**********
Dear Farzaneh,

This is actually a great question! We have forwarded your question to Clint Penick (photo of Clint with a large wood ant thatch mount at the end of this post), who has studied thermoregulation in some ant species. Here is his response:

"Ants are ectotherms (or "cold-blooded"), which means that they rely on their environment for thermoregulation. This can be seen in their nest structure. Ants usually construct deep, underground nests that maintain fairly stable temperatures. In the summer, ground temperatures provide shelter from the heat, and in the winter the ground is warmer than the outside air. The winter ant, Prenolepis imparis, builds some of the deepest nests known to ants (close to 12 feet or 3.6 meters below the surface), and these ants retreat to the cool shelter of their nests during the summer and only come to the surface during cooler months.

Many ants build their nests under rocks, which can serve as solar collectors. This is why ant researchers are sometimes called "rock flippers," because many species of ants can be found under rocks, especially in the morning when these rocks begin to heat up. Because rocks often stick above the ground surface, they have a lower specific heat than the surrounding ground. This means that they will heat up faster during the day-even under shady conditions-but they also cool down faster at night.

Some ants have developed special nest structures that aid in thermoregulation. These ants are the "mound builders." The fire ant, Solenopsis invicta, builds a mound out of soil, which is riddled with a spongiform network of tunnels. These mounds serve the same function as rocks-they collect solar thermal energy and have a reduced specific heat so they heat up faster than the ground. Fire ant larvae grow best at 32ºC, so workers move their larvae up to the surface of the mound early in the morning as the mound begins to heat up. By mid day, the surface of the mound is too hot, so the ants move the larvae deeper into the nest to track the optimal temperature. By nightfall, all of the larvae and most of the colony is located deep underground where temperatures are more stable. In fact, this behavior is so reliable it can be used as a natural compass: the ants bring all their larvae to the south side of the nest in the morning, where the sun's rays are the strongest. To see an example of a mound nest of the fire ant, check out this previous post here.

The species that build the largest mounds, however, use a completely different process. These ants, which are called "thatch builders," live in northern Europe and Scandinavia. Thatch mounds can be over two meter tall and are built out of decaying pine needles and leaves. Like a compost pile, the leaves of the mound release heat as they decompose, and this plant material also provides insulation. While fire ant mounds reach their highest temperatures on the outer surface, thatch mounds are warmest near the center of the mound where the heat from decomposition is the strongest. In addition to the mounds, thatch ants also use their own bodies to heat the interior of their nests. Worker ants sun themselves on the surface of the mound and then quickly run inside to heat up the interior of their nest with their warm bodies. To see an example of a thatch nest of a wood ant, check out this previous post here.

Other insects, like honey bees, can generate internal body heat by flexing their flight muscles. Ants don't have flight muscles, but their bodies do produce a limited amount of heat. Army ants, like Eciton burchelli, don't dig nests in soil, but instead construct hanging bivouacs out of their own bodies. They are able to use the collective heat of their bodies to keep warm over night, and they can adjust their position to allow ventilation during the day.

Honey bees can also ventilate their nests by using their wings like fans. Again, ants don't have wings, so they use different methods for nest ventilation. The massive colonies of Atta fungus-gardening ants are topped with a dome of soil that has small chimneys. As winds blow over the nest, convection over the chimneys pulls stagnant air out of the nest and allows fresh air to flow back inside. This has a negligible effect of nest temperature, but it does help cycle CO2 out of the nest and increase oxygen levels inside."

Clint Penick (guest expert), Steffi Kautz & the AntAsk Team

Hi AntAsk,

What specific dates (time frame) do harvester ants have to gather their food before winter strikes?

Best,
Javier

Dear Javier,

Thank you very much for your great question. We have contacted Christina Kwapich, who has done some great work on harvester ants, to address your query. Here is what she had to say:

"While there are numerous genera and species of seed harvesting ants, none is more charming (or easier to exhume) than the Florida harvester ant (Pogonomyrmex badius). Populations of P. badius dapple the coastal plain, east of the Mississippi river and favor spots with well drained, sandy soil. Between March and November of each year foragers seek out seeds, insect protein and even freshly cut slivers of fungus to feed crops of hungry larvae. Seeds are the only physical products that colonies store over winter and some colonies really know how to fill the pantry! Walter Tschinkel noted that one large P. badius colony housed over one pound of seeds (Tschinkel 1999). While we don't yet know how long the oldest seeds remain in P. badius seed caches, Preliminary data from the Tschinkel lab show that fresh seeds are frequently processed within days of collection, while some apparently 'uncrackable' seeds linger indefinitely. This means that the old "first in first out" adage may not apply when it comes to stocking the shelves in an ant nest.

Although numerous chambers brim with seeds all winter long, adults don't appear to ingest a morsel of the spoils. It might be tempting to exalt them for their willpower, but the truth is that the narrow waists of adult ants prevent them from ingesting solid food. In fact, seeds and other solid food items are collected expressly for consumption by hungry larvae; which only appear from April to November of each year. In the absence of a liquid diet, adult P. badius workers rely on ample fat reserves to tide them over the winter months. The age of adults entering the over-wintering period ranges from 10 to 60 days, but whether or not these individuals consume a special diet in preparation for the long stretch is unknown (Kwapich and Tschinkel, unpublished). We do know that when winter begins, workers enter a period of reduced activity, abandoning their posts across many meters of vertical nest space to occupy only the bottom-most chambers (a cozy 24 degrees Celsius, all year round, i.e., 75 degrees Fahrenheit).

The presence of winter seed caches may lead one to believe that seeds play a key role in springtime alate (those are the winged sexuals in ants that form the next generation) and worker production. Surprisingly, Chris Smith (2007) demonstrated that when prevented from foraging, colonies did not tap into their ample seed reserves and use them as a buffer against starvation. Instead, it appears that spring-time worker fat-reserves (garnered in autumn) are most important to the production of alates and new workers following winter. So, to answer the original question, it appears that P. badius workers spend nine months adding and subtracting from a large seed cache which may be of no critical importance at all! This should not be entirely befuddling, as Willard and Crowell (1965) noted that another seed harvester, Pogonomyrmex owyheei, successfully enters and exits winter without stored products of any kind."

All the best,
Christina Kwapich (guest expert), Steffi Kautz & the AntAsk Team

Works cited:

Smith, C. R. (2007). Energy use and allocation in the Florida harvester ant, Pogonomyrmex badius: are stored seeds a buffer? Behavioral Ecology and Sociobiology 61:1479-1487.

Tschinkel, W. R. (1999). Sociometry and sociogenesis of colony-level attributes of the Florida harvester ant (Hymenoptera: Formicidae). Annals of the Entomological Society of America 92: 80-89.

Willard, J. R. & H. H. Crowell (1965). Biological Activities of the Harvester Ant, Pogonomyrmex owyheei, in Central Oregon. Journal of Economic Entomology 58:3.

Hello,
I teach at a high school in Australia and I'm currently doing a unit on ants. One of the students in the class lives on a farm where there are lots of black ants. He and his family (I spoke to his father after school and he confirmed that his son was not kidding) have observed that ants seem to know when the rains are coming "weeks, even up to a month before they actually arrive." He says that they start preparing by storing food and building up walls around the nest.

The class found this fascinating and wanted to know how the ants could possibly know the rains were coming so far in advance. I told them that antweb are an authority on ants and that I would write to you for an explanation. My first question is: Is it possible that the ants could know the rains were coming so far in advance? Secondly, if so, how are they able to do this. Thirdly, if the student and his family are wrong, what are they observing that leads them to believe that the ants are long term weather changes?

My class and I would greatly appreciate any insights you are able to offer on this topic.

Kind regards,

Max

Dear Max,

Thanks for your question!
There are a variety of ways that human meteorologists can predict the weather: they can look at trends in barometric pressure, they can note the wind direction and look at the clouds (from the ground or from satellites). But they can also make general predictions based on past trends. I suspect that any meteorologist in your area could predict to the nearest 10 days when the first monsoon rains are likely to hit southeastern Queensland, and they wouldn't need any information at all about the current weather! In many areas of the world, there are predictable times of year that organisms need to prepare for or migrate away from--times of year that are either too cold, too hot, too wet, or too dry for organisms to function well. Some organisms whose ancestors have been living in those places for millions of years are adapted to the annual rhythm of these seasons. The ants your student and his family observed are not "predicting" the weather any more than migratory birds or blossoming flowers are--they're just behaving in a way that is adaptive to long periods of rainfall.

Many animals and plants (and perhaps other organisms, like marine algae) have an instinctual response to seasonal cues like light levels or day length (photoperiod). For example, cherry trees from certain parts of Asia will always flower when days are as long as they are at the beginning of spring in that part of Asia. For other plant species, budding occurs only after some threshold of both photoperiod and temperature has been passed, and bird migration may be regulated by an even more complex interplay of cues, including food abundance. It has even been proposed that organisms might have "circannual clocks," the annual version of our circadian rhythms that get messed with when we travel to a new time zone. For many species, the exact cues used to regulate annual cycles of behavior and life history (or phenology) are not understood.

I'm sure you've guessed by this point that I don't know exactly what cues the ants on your student's farm are responding to. But as a class, you might be able to perform some scientific experiments to figure it out! My understanding is that your rainy season is the Austral summer--the warmer time of the year, with longer days. Thus, two cues the ants might be using (separately or together) are the length of the days and the temperature. If there are many of these ant nests, then you could set up lights around some nests about half way through the winter, and put them on a timer so that they turned on a half hour before dawn and again a half hour after dark. Near other nests, you could place some "heat rocks," like those used for reptiles. Some nests could receive both treatments, and some nests neither. Then you could see if any of the ant nests "predict" that the rains will come earlier than others. Unfortunately, you might have to wait until next year to perform this experiment, but, hey, it doesn't hurt to plan ahead, right?

One reason phenology and chronobiology are such "hot" topics lately is that global climate change is likely to make things difficult for organisms that use photoperiod as a cue to adjust to the changing of the seasons. Perhaps you and your class (or future classes) could help us better understand how the ants of Australia will react to climate change!

Hope this helps!
best,
Jesse Czekanski-Moir & the AntAsk Team

Hello AntBlog team,

I have a few questions and I was wondering if you could help me?

I recently acquired a small colony of Camponotus morosus, I housed the colony inside an aerated autoclaved concrete nest, however just after the colony had moved in I was taking photos and noticed what appear to be very large (In ant terms) mites, I have only noticed 2 of the mites in the colony so far, the thing is I cannot manually remove the mites unless the workers come out to forage with them on as the nest is affixed to the inside of a glass tank.

Strangely the mites only seem to attach to the very small minor workers who do not leave the nest to forage, they are mobile and I have seen them moving from one ant to another and they always latch on the underside of the ant, they do seem to bother the worker they latch on to.

I was wondering if you could give me any information on these mites as they are unlike any ant associated mites I have come across before.

How can I get rid of them? Are they parasitic or phoretic? Will they hurt my colony?

And finally if you have any information on C. morosus you could give me I would really appreciate it, I'm afraid I have not been able to find a lot of information out on the internet as of yet!

Regards,
~Daniel

*****
Dear Daniel,

Wow! Those mites are really amazing! We contacted a colleague, Kaitlin U. Campbell, who is an expert in mites found on ants to see what she had to say:

"Dear Daniel,

Thanks for sending the great pictures of these exciting mites you found! As you might imagine mites are pretty difficult to identify from images, and the specimens typically must be mounted on microscope slides to get accurate identifications. You are correct about these being very large mites (in terms of ants on mites). There are very few people working on mites associated with South American ants that aren't army ants, and to my knowledge none of them have looked at Camponotus. If this mite is truly associated with Camponotus morosus and not just there by accident, it is likely a new species. The best identification I can give you from these pictures is that it is in the Mesostigmata. Unfortunately this doesn't provide much information in terms of what they are doing. Here is a summary we do know about ant associated mites:

The majority of ant associated mites typically fall into 3 subgroups of mites: Mesostigmata, Heterostigmata, and Astigmata. All of these groups have members that ride on the ants (phoresy). Astigmata and Heterostigmata are typically smaller in size than the Mesostigmata. The Astigmata and Heterostigmata that I have encountered are generally believed to be fungivores or bacterivores taking advantage of the resources inside the ant nests, and possibly cleaning up when they are not riding on the ants. There are only a few genera of Heterostigmata that are known parasites. Because of their mouth parts and what little we know of their ecology, we believe these two groups are the least likely to cause any harm to the ants. In fact the phoretic Astigmata (their Deutonymph stage) do not even have mouths and only get mouths when they develop to the next stage after the disembark from the host!

The Mesostigmata, however, are a different story. Many of these have large enough mouth parts that they could actually cause damage to the hosts. The majority of the "mesostigs" are still thought to just use the host to get around (they are probably predators of other mites, Collembola, and nematodes or scavenging in the nests), but a few are known to pierce the hosts' cuticles or feed on brood. As you can image, mite behavior is difficult to study, so few have actually looked into this in detail. The most well studied Mesostigs are either associates of Army ants (many of which have really unusual body shapes), Macrodinychus species parasitizing developing brood, or Antennophorus species a cleptoparasite (steals food) on Lasius ants. What you have is not any of these! Yours looks most similar to the Antennophorus species, and may be in the same Suborder, but without having the specimen on a slide it's not going to be possible to tell.

Concerning whether they are bad for your colony- As I mentioned before, very few mites are known to actually cause damage to their ant hosts. I am suspicious of your mites, however, because of their orientation on the ants. They seem to be positioned in areas with their heads near soft tissue, and you said they do seem to bother the ants. The ants could just be bothered because the mites are large and cumbersome to be carrying around, though. They could potentially be harming the ants, and you should monitor the mites behavior and the health of your ants. It's very difficult to get rid of mites on the ants without harming the ants with any chemicals. Since you only have a couple it would be best to just remove them individually from the ants if you can ever get the small ants to exit the nest area. If they are seriously harming the colony, your only option may be to open the nest and remove the ants carrying the mites. I would just watch them closely and resort to active removal if they seem to cause a lot of damage.

If you are able to remove the mites and interested in knowing what they are (I sure am!), please preserve them in ethanol and send them to me and/or take individual pictures of the dorsal and ventral sides of the mites.

This is a cool find, and I'll be interested to hear more! I hope this helped!"

Best regards,
Kaitlin U. Campbell (guest expert), Corrie Moreau & the AntAsk Team

Hi:

Looking at tiny bugs, I have always wondered whether big ones, having much bigger brains or at least room for them, are "smarter" than small ones.

In answer to a question about the largest ant, you mention some that are 3 cm long, compared to the smallest that are <1mm. That is a length ratio of 30 times, which means mass and volume differ by 30^ 3 = 27,000 times. This is consonant with what you imagine, looking at a barely visible member of the phylum we kids called "piss ants" (which I'm sure is the Latin technical term!)

A 3 cm ant is like a roach or other bug and you don't expect it to be very smart, but it probably does have a large hard-wired repertoire of behaviors -- forage, fight, mate etc. But at 1 mm, brain shrunk 27,000 times, you have to wonder whether there are enough neurons to code for all that. Is there some limiting size beyond which bugs get dumber? I recall from high school biology fifty years ago that bugs probably don't have brains per se, but several ganglions (ganglia?), and most of the cells therein are used to drive muscles, so it's proportional and a small ant needs only a small ganglion for that. But for seeing and behavior and the like there must be a minimum number of neurons required.

So -- how tiny can they be before they start to get dumber?

Alan
**********

Dear Alan,

To address your question about ant brains, we contacted one of your colleagues who is an expert on ant brains, Dr. James Traniello, and here is what he had to say:

"First of all, insects do have well-structured brains made of compartments of tissues with specialized functions in visual and odor information processing, motor control, and learning and memory! Only a small portion of the brain (and ganglia) appear to control muscles.

It's been a great challenge to understand the relationship between the structure and function of the brain and whether or not small size compromises processing ability and "intelligence." It's been assumed, particularly in vertebrates, that brain size and cognitive ability go hand-in-hand, but animals with larger brains are not necessarily "smarter." There is no question that tiny insect brains can generate complex behavior (In this respect, Charles Darwin thought the ant brain was more marvelous than the human brain). It's an open question as to how many neurons are needed to generate complex behavior. Some models suggest very few nerve cells are required for learning, for example.

Social life and ecology affect the evolution of brain size; body size alone does not appear to be a very good predictor of cognitive ability. Larger worker ants don't appear to be any "smarter" than small workers and any differences in behavior, especially learning and memory, are likely due to differences in their foraging ecology rather than their size per se. Larger ants may, for example, hunt for prey and have better vision, and this ability is reflected in the size of the optic lobes of the brain that process prey stimuli. Small ants may have relatively large brains, and different ant species have brain compartment proportions that fit their ecology and behavior.

It's also important to remember that ants are collectively intelligent: they solve problems as communicating groups. How this group intelligence affects brain evolution is not well understood. Ants with large colonies may have workers with relatively smaller brains. The smallest bodied ants may have fewer cognitive abilities as individual workers, but their colonies may be just as "smart" as colonies of ant species that have larger body size. "Intelligence" has to be considered in respect to ecology, social behavior and life history in all animals."

To see an image of an ant brain, please see the home page of Dr. Traniello's lab website: http://people.bu.edu/jftlab/Home.html

Best regards,
James Traniello (guest expert), Corrie Moreau, & the AntAsk Team